Djokovic matches Lendl's 29-match winning start

Novak Djokovic from Serbia celebrates during the match against Guillermo Garcia-Lopez at the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

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Novak Djokovic from Serbia celebrates during the match against Guillermo Garcia-Lopez at the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

Novak Djokovic from Serbia celebrates during the match against Guillermo Garcia-Lopez at the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki) (/ AP)

PAUL LOGOTHETIS, AP Sports Writer

Francesca Schiavone from Italy reacts during a match against Bethanie Mattek-Sands from U.S. in the Madrid Open tennis tournament in Madrid, Spain, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

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Francesca Schiavone from Italy reacts during a match against Bethanie Mattek-Sands from U.S. in the Madrid Open tennis tournament in Madrid, Spain, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

Francesca Schiavone from Italy reacts during a match against Bethanie Mattek-Sands from U.S. in the Madrid Open tennis tournament in Madrid, Spain, Thursday, May 5, 2011.(AP Photo/Andres Kudacki) (/ AP)

Bethanie Mattek-Sands from U.S., left, embraces Francesca Schiavone from Italy during the match in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

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Bethanie Mattek-Sands from U.S., left, embraces Francesca Schiavone from Italy during the match in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

Bethanie Mattek-Sands from U.S., left, embraces Francesca Schiavone from Italy during the match in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki) (/ AP)

Francesca Schiavone from Italy serves during the match against Bethanie Mattek-Sands from U.S. in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

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Francesca Schiavone from Italy serves during the match against Bethanie Mattek-Sands from U.S. in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

Francesca Schiavone from Italy serves during the match against Bethanie Mattek-Sands from U.S. in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki) (/ AP)

Juan Monaco from Argentina returns the ball during the match against Tomas Berdych from Czech Republic in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

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Juan Monaco from Argentina returns the ball during the match against Tomas Berdych from Czech Republic in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

Juan Monaco from Argentina returns the ball during the match against Tomas Berdych from Czech Republic in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki) (/ AP)

China's Na Li celebrates a point during her Madrid Open tennis tournament match against Italy's Roberta Vinci, in Madrid, Thursday, May 5, 2011.(AP Photo/Daniel Ochoa de Olza)

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China's Na Li celebrates a point during her Madrid Open tennis tournament match against Italy's Roberta Vinci, in Madrid, Thursday, May 5, 2011.(AP Photo/Daniel Ochoa de Olza)

China's Na Li celebrates a point during her Madrid Open tennis tournament match against Italy's Roberta Vinci, in Madrid, Thursday, May 5, 2011.(AP Photo/Daniel Ochoa de Olza) (/ AP)

Thomaz Bellucci from Italy celebrates during the match against Andy Murray from Great Britain in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

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Thomaz Bellucci from Italy celebrates during the match against Andy Murray from Great Britain in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

Thomaz Bellucci from Italy celebrates during the match against Andy Murray from Great Britain in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki) (/ AP)

Andy Murray from Great Britain reacts during the match against Thomaz Bellucci from Italy in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011. (AP Photo/Andres Kudacki)

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Andy Murray from Great Britain reacts during the match against Thomaz Bellucci from Italy in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011. (AP Photo/Andres Kudacki)

Andy Murray from Great Britain reacts during the match against Thomaz Bellucci from Italy in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011. (AP Photo/Andres Kudacki) (/ AP)

Jo-Wilfried Tsonga from France sits on court during the match against Robin Soderling from Sweden in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

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Jo-Wilfried Tsonga from France sits on court during the match against Robin Soderling from Sweden in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

Jo-Wilfried Tsonga from France sits on court during the match against Robin Soderling from Sweden in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki) (/ AP)

Serbia's Novak Djokovic returns the ball during the match against Spain's Guillermo Garcia-Lopez in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

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Serbia's Novak Djokovic returns the ball during the match against Spain's Guillermo Garcia-Lopez in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

Serbia's Novak Djokovic returns the ball during the match against Spain's Guillermo Garcia-Lopez in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki) (/ AP)

Bethanie Mattek-Sands from U.S. returns the ball during her match against Francesca Schiavone from Italy duriong the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

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Bethanie Mattek-Sands from U.S. returns the ball during her match against Francesca Schiavone from Italy duriong the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

Bethanie Mattek-Sands from U.S. returns the ball during her match against Francesca Schiavone from Italy duriong the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki) (/ AP)

Bethanie Mattek-Sands from U.S. celebrates during her match against Francesca Schiavone from Italy during the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

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Bethanie Mattek-Sands from U.S. celebrates during her match against Francesca Schiavone from Italy during the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

Bethanie Mattek-Sands from U.S. celebrates during her match against Francesca Schiavone from Italy during the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki) (/ AP)

Serbia's Novak Djokovic returns the ball during the match against Spain's Guillermo Garcia-Lopez in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

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Serbia's Novak Djokovic returns the ball during the match against Spain's Guillermo Garcia-Lopez in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki)

Serbia's Novak Djokovic returns the ball during the match against Spain's Guillermo Garcia-Lopez in the Madrid Open tennis tournament in Madrid, Thursday, May 5, 2011.(AP Photo/Andres Kudacki) (/ AP)

Novak Djokovic extended his season-opening winning streak to 29 matches Thursday at the Madrid Open, equaling the best start in men's tennis in 25 years.

Djokovic, who is 31-0 since last year's Davis Cup final, is tied for third with Ivan Lendl for the best season start since 1980. John McEnroe won 42 straight to start the 1984 season, and Bjorn Borg won 33 in a row at the beginning of the 1980 season.

"I know I'm playing great now but there is always something you can improve on - you can never be perfect," the Serbian player said. "I'm winning service games comfortably. That's something I'm happy about today and an encouraging fact for upcoming matches, especially on clay."

Mattek-Sands - sporting knee-high socks and black mascara under her eyes - will play Australian Open finalist Li Na after the Chinese player rallied to defeat Roberta Vinci of Italy 2-6, 6-2, 6-1.

"I'm really happy with my play on clay right now," Mattek-Sands said. "I feel like a true dirtballer."

Federer was in total control after being pushed to the limit one night earlier, when the third-ranked Swiss player was forced to save a match point.

"Mentally I had to shift a bit. I just wanted to put in a good performance, which is what I did," Federer said. "It was a quick turnaround. I just had to get past this match today to have the quarters in sight."

Del Potro pulled out after feeling discomfort in his left hip. With his participation at the French Open at stake, Del Potro preferred not to risk another injury after wrist surgery sidelined him for most of last year.

"It's not nice to have to withdraw from this tournament and this game, which would have been nice to play but I'm not in shape," said the 32nd-ranked Argentine, who dropped to No. 481 in January before winning in Delray Beach and Estoril. "I tried but I'm not in shape to play."

Meanwhile, Murray was visibly frustrated by Bellucci's play as the Brazilian used four aces to help save all three of Murray's break points.

Earlier, Goerges rallied from 3-0 down to take the first set against Wozniacki after breaking twice. But she lost that momentum as the top-seeded Dane leveled the match with two breaks of her own in the second set.

The 27th-ranked German player broke Wozniacki in the eighth game of the deciding set to lead 5-3 before serving out the match. Goerges, who beat Wozniacki in the Porsche Grand Prix final last month, had 36 winners to her opponent's 11.

"I beat her twice and twice in two weeks, so I'm pretty proud of myself," she said.